I just came across an article from my old JOHO newsletter, from May 2005, that I wrote for Esther Dyson’s Reality 1.0. It was titled Trees and Tags— An Introduction, and it was about the limitations of taxonomies and the rise of tags. I must have been writing or researching Everything Is Miscellaneous at the time.

Here’s the introductory section. If you’re interested in ancient history, you can read the whole thing.

The Three Orders

The narrative that tells of the first man and woman encountering the tree of knowledge focuses on its tempting fruit. But after we took the bite, we apparently looked up and got the idea that knowledge is shaped like the tree’s branching structure: Big concepts contain smaller ones that contain smaller ones yet. Over the millennia, we have fashioned the structures of knowledge in just such tree-like ways, from the departmental organization of universities (liberal arts contains history and history contains ancient Chinese history) to the hierarchy of species. The idea that knowledge is shaped like a tree is perhaps our oldest knowledge about knowledge.

Now autumn has come to the forest of knowledge, thanks to the digital revolution. The leaves are falling and the trees are looking bare. We are discovering that traditional knowledge hierarchies that have served us so well are unnecessarily restricted when it comes to organizing information in the digital world. The principles of organization themselves are changing now that they are being freed from the constraints of the physical world. For example:

In the physical world, a fruit can hang from only one branch. In the digital world, objects can easily be classified in dozens or even hundreds of different categories.

In the real world, multiple people use any one tree. In the digital world, there can be a different tree for each person.

In the real world, the person who owns the information generally also owns and controls the tree that organizes that information. In the digital world, users can control the organization of information owned by others. (Exception to the rule: Westlaw owns the standard organization of case law even though the case law itself is in the public domain.)

These differences are so substantial that we can think of intellectual order as entering a third age. In the first, we organized the things themselves: We put books on shelves and silverware into drawers. In the second, we physically separated the metadata from the data: We built card catalogs and drew diagrams. In the third, the data and the metadata are digital, untying organization from the strictures of the physical world. In response, we are rapidly inventing new principles and tools of organization. When it comes to innovation on the Internet, metadata is becoming the new content.

But traditional taxonomic trees aren’t something we can throw away without a thought. They are an amazingly efficient way of organizing complexity because they enable us to focus on one aspect (e.g., that’s an apple) while keeping a universe of context (it’s a fruit, part of a plant, a type of living thing) in the background, ready for access. Tree structures are built into our institutions. They may even be built into our genes. So we are in a confusing and fertile period as we try to sort out what works and what doesn’t. Without trees, how would we organize college curricula, business org charts, the local library, and the order of species? How will we organize knowledge itself?